In plant physiology, the epicotyl is the embryonic shoot above the cotyledons. In most plants the epicotyl will eventually develop into the stem and the leaves of the plant. In dicots, the hypocotyl is what appears to be the base stem under the spent withered cotyledons, and the shoot just above that is the epicotyl. The hypocotyl is what develops into the roots of the plant. In monocot plants, the first shoot that emerges from the ground or from the seed is the epicotyl, from which the first shoots and leaves emerge.
In sunflower seedlings, the difference between epicotyl and hypocotyl can be seen from the parts of the stem divided by the first pair of leaves. Here the stem above the cotyledons is covered in tiny hairs whereas the region of stem below (hypocotyl) is smooth.
Lengthening of the epicotyl is thought to be controlled by the phytochrome photoreceptors.
Mixture screening and mixture-amount designs to determine plant growth regulator effects on shoot regeneration from grapefruit (Citrus paradisi macf.) epicotyls
Dec 01, 2011; Abstract The objective of this study was to improve shoot regeneration from grapefruit. Because many commercially grown citrus...